This application is based on and claims priority under 35 U.S.C. xc2xa7 119 with respect to Japanese Application No. 2001-086092 filed on Mar. 23, 2001, the entire content of which is incorporated herein by reference.
This invention generally relates to a closed space monitor system. More particularly, the present invention pertains to a closed space monitor system for monitoring a closed space such as the inside or interior of a parked vehicle.
Various proposals have been made for closed space monitor systems for detecting the presence of intruders in closed spaces such as inside of a parked vehicle. Known closed space monitor systems include a device having a door sensor which performs intrusion detection by detecting a change of an output (i.e., potential), a device which performs intrusion detection by generating an ultrasonic wave and detecting the presence of a reflected wave thereof in the vehicle, and a device which performs intrusion detection by detecting intruders through use of the Doppler effect of the ultrasonic wave and the radar.
However, the aforementioned known closed space monitor systems are susceptible to temperature changes and electromagnetic noise. Consequently, the reliability of the intrusion detection performance of these known closed space monitor systems is relatively low.
With specific regard to the closed space monitor system for detecting the intruders through use of a door sensor, if the wiring is bypassed for not generating the change of the potential, the system is invalidated. Concerning the closed space monitor system that detects intruders by the presence of the reflection wave of the ultrasonic wave, the monitoring performance of the entire closed space is insufficient in light of the dead area formed by, for example, the seats in the interior of the vehicle.
With respect to the closed space monitor system that detects intruders by the Doppler effect of the ultrasonic wave and the radar, the system may not react to a slowly moving object (i.e., an intruder). In addition, with respect to the closed space monitor system for detecting the intruders with the infrared radiation, the system may cause operational error by the incoming radiation of the sun and the exposure to light.
A need thus exists for a closed space monitor system for monitoring the presence of intruders that is not as susceptible to the disadvantages and drawbacks noted above.
According to one aspect, a closed space monitor system includes a transmitter for generating and transmitting a compression wave of gas, a receiver for receiving the compression wave of gas, and an amplifier portion for amplifying a signal transmitted from the receiver. The amplified signal from the receiver is transmitted from the transmitter for generating a stationary wave in the closed space.
According to another aspect, a closed space monitor system in a vehicle detects the occurrence of an intrusion into a closed space in the vehicle. The system includes a transmitter for generating and transmitting a compression wave of gas, a receiver for receiving the compression wave and transmitting a signal, and an amplifier which amplifies the signal transmitted from the receiver, with the amplified signal from the receiver being transmitted from the transmitter for generating in the closed space of the vehicle a stationary wave having an amplitude value and an effective value. A judging mechanism judges the occurrence of an intrusion into the closed space of the vehicle based on a fluctuation of the amplitude value of the stationary wave or the effective value of the stationary wave.